In current code-division multiple access (CDMA) communication systems, the handoff of a mobile station's communication from one frequency to another frequency, referred to as "hard handoff," presents a problem. The biggest problem presented during a CDMA hard handoff is due to MAHO (Mobile Assisted Handoff). Specifically, it is difficult for the mobile station to determine the location at which hard handoff should take place. One solution to the hard handoff problem in CDMA is to use a so-called "beacon signal" to cause mobile stations to "soft handoff" (i.e., handoff from one frequency spread with one pseudo-noise (PN) offset) to the same frequency with a different PN offset. Typically, the source and the target channels are separated by a boundary and are in different areas of the CDMA cellular radiotelephone system, or could be operated separately by two separate operators. After a soft handoff occurs over the boundary, a hard handoff within the common target CDMA cellular radiotelephone system is performed as is known in the art.
Problems with the beacon signal solution remain. For example, for CDMA communication systems which are multi-frequency, one corresponding beacon signal is required for each frequency provided by the source CDMA communication system. This problem is magnified when both the source and the target CDMA communication systems become sectorized. Finally, providing additional transmitters corresponding to the multi-frequencies of the source CDMA cellular radiotelephone system is costly since a dedicated transmitter is required to transmit each beacon signal.
Thus a need exists for an apparatus and method which overcome the deficiencies of the prior art.